Unidirectional gene flow and the maintenance of genetic diversity in the mosquitofish Gambusia holbrooki (Teleostei: Poeciliidae)

Congdon, Brad (1995) Unidirectional gene flow and the maintenance of genetic diversity in the mosquitofish Gambusia holbrooki (Teleostei: Poeciliidae). Copeia, 1995 (1). pp. 162-172.

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Spatial and temporal variation in allele frequencies at a locus for glucose-6- phosphate isomerase (GPI-2) were examined among populations of Gambusia holbrooki inhabiting an intermittent stream in southeast Queensland, Australia. Instream distance explained up to 68% of observed genetic variation; distance effects were modified by barriers that allowed only downstream movement during peak flooding. Different alleles occurred at high frequencies in the headwaters of each catchment. Predominance of a single allele in headwater populations was attributed to absence of upstream movement and the ephemeral nature of headwater populations. Headwater alleles were the most common alleles in lower reach populations. Intercatchment differences were attributed to random fixation of different alleles in headwater populations, followed by dispersal of alleles downstream during peak flood events. Multiple alleles were maintained in lower reach populations by immigration from tributaries where alternative alleles presumably had drifted to high frequencies. Differentiation among lower reach populations fluctuated annually as a function of immigration entering lower sites from alternative upstream sources. Immigration from source populations was related to flow velocity in tributaries converging above lower sites. Allele frequency changes associated with saltwater inundations maintained genetic differences among lower reach populations during periods of low flow and isolation. Saltwater effects were inconsistent and could not compete with gene flow during periods of high flow velocity.

Item ID: 28827
Item Type: Article (Research - C1)
ISSN: 1938-5110
Date Deposited: 27 Aug 2013 00:26
FoR Codes: 06 BIOLOGICAL SCIENCES > 0604 Genetics > 060411 Population, Ecological and Evolutionary Genetics @ 30%
05 ENVIRONMENTAL SCIENCES > 0501 Ecological Applications > 050103 Invasive Species Ecology @ 70%
SEO Codes: 96 ENVIRONMENT > 9604 Control of Pests, Diseases and Exotic Species > 960406 Control of Pests, Diseases and Exotic Species in Fresh, Ground and Surface Water Environments @ 100%
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